基于核磁共振T2谱图的裂隙砂岩疲劳损伤分析

doi:10.11872/j.issn.1005-2518.2020.03.151

摘要/Abstract

摘要：

岩石工程中岩体经常处于周期性的力学行为作用下，研究裂隙岩体在疲劳加载下的损伤变化具有重要的工程意义。选取了5种裂隙倾角的黄砂岩试样进行疲劳试验，采用核磁共振仪器分别测得各倾角裂隙砂岩在不同疲劳上限应力作用下30个疲劳循环前后其内部的孔隙变化情况，发现大孔隙数量随疲劳上限应力的增加呈指数增长，是造成裂隙砂岩疲劳加载后孔隙度增大的主要因素。定义了2种基于大孔隙占总孔隙比值的损伤变量来研究疲劳上限应力对各裂隙倾角砂岩的疲劳损伤影响，均能较好地反映损伤变量随疲劳上限应力的变化情况，得出损伤变化趋于平缓的裂隙岩样最终破坏时的强度大于损伤变量陡增的裂隙岩样。最后从理论角度分析得出孔隙与轴向应变之间存在正相关关系，即用孔隙反映砂岩疲劳损伤是合理的。

关键词: 裂隙砂岩, 疲劳加载, 核磁共振, 微观损伤, 疲劳强度, 损伤变量

Abstract:

In the process of underground mining and tunnel construction，the rock is mostly in the process of repeated loading and unloading，and the macro-cracks and micro-defects in the rock mass itself will continue to expand under fatigue loading and eventually lead to many accidents.Therefore，it is of great engineering significance to study the micro-defects of fractured rock masses under fatigue loading.In the previous studies, acoustic emission and CT scanning technology were mainly used to reflect the change of microscopic damage through AE number or CT number, which obtained good results.The porosity measured by nuclear magnetic resonance technology can also be used to show the damage of rock samples，but it is currently mainly used in uniaxial compression loading.In this experiment，yellow sandstone specimens with five fracture inclination angles （0°，15°，30°，45°，60°） were selected.Firstly，uniaxial compression experiments were performed to measure the uniaxial compressive strength of fractured sandstone at various angles.Then carry out fatigue loading experiments，and select the upper limit fatigue loading stresses based on the measured uniaxial compressive strength to be 19.1 MPa,25.6 MPa and 30.3 MPa，respectively.The internal porosity of each fractured sandstone before and after 30 fatigue cycles under each upper limit stress was measured with nuclear magnetic resonance instruments.Combined with the analysis of T₂ spectrum measured by nuclear magnetic resonance instrument，it is found that with the increase of the upper limit stress，the total area of T₂ spectrum and the accumulation of porosity in fractured sandstone have increased significantly.This shows that its internal damage increases with the increase of the upper limit stress，and then combined with the T₂ spectral area for quantitative analysis，it was found that the spectral area of the small pores in the T₂ spectrum changed only slightly with the increase of the upper limit stress，while the spectral area of large pores increases exponentially with the increase of the upper limit stress.No matter from the angle of the change of the ratio of large pores (to the total pores) to the fatigue upper limit stresses under different inclination angles，or from the angle of the change of the ratio of large pores under different fatigue upper limit stresses to the angle of fracture inclination，similar rules are obtained.Therefore，it can be concluded that the change of large pores is the main factor that causes the total porosity of fractured sandstones to increase after fatigue loading，and then the curve of the ratio of the proportion of large holes to the upper limit fatigue stress ratio after fatigue loading at various inclination cracks is fitted.The fitting coefficients of sandstones at various inclination angles are very high，which shows that the change law of internal damage can be well displayed.Considering the effect of initial damage of rock samples on fatigue loading，two types of damage variables based on the ratio of large pores to total pores were defined to study the impact of fatigue upper limit stress on the fatigue damage of sandstones with different fracture inclination angles.According to the relationship curves between the two damage variables，the upper limit stress ratio and the upper limit stress，the change of the defined damage variable can be well projected. Further analysis can show the intensity change of the sandstones with different fracture inclination angles，that is，the damage intensity of the fractured rock sample that tends to be gentle will eventually be greater than that of the fractured rock sample with a sharp increase in damage. Finally，combining the probability density function of Weibull distribution and generalized Hook’s law，it is deduced from the theoretical formula that it is reasonable to use pores to study sandstone fatigue damage.Combining the results of previous studies and this experiment，it was found that the porosity can well reflect the microscopic damage of rock samples in both uniaxial compression experiments and fatigue loading experiments.

Key words: fractured sandstone, fatigue loading, nuclear magnetic resonance, microscopic damage, fatigue strength, damage variable

中图分类号:

TU443

毛思羽, 曹平, 李建雄, 欧传景. 基于核磁共振T₂谱图的裂隙砂岩疲劳损伤分析[J]. 黄金科学技术, 2020, 28(3): 430-441.

Siyu MAO, Ping CAO, Jianxiong LI, Chuanjing OU. Fatigue Damage Analysis of Fractured Sandstone Based on Nuclear Magnetic Resonance T₂ Spectrum[J]. Gold Science and Technology, 2020, 28(3): 430-441.

图/表 14

图1

图2

图3

图4

图5

表1

图6

图7

图8

表2

表3

图9

表4

图10

参考文献 24

1	苏承东，杨圣奇.循环加卸载下岩样变形与强度特征试验 [J].河海大学学报（自然科学版），2006，34（6）：667-671.
	Su Chengdong，Yang Shengqi.Experimental study on deformation and strength characteristics of rock samples under cyclic loading and unloading[J].Journal of Hohai University（Natural Science Edition），2006，34（6）：667-671.
2	史贵才，葛修润，卢允德.红砂岩应力脆性跌落系数的试验研究[J].常州工学院学报，2007，20（6）：1-6.
	Shi Guicai，Ge Xiurun，Lu Yunde.Research on coefficent of brittle stress drop of red sandstone[J].Journal of Changzhou Institute of Technology，2007，20（6）：1-6.
3	卢应发，葛修润.岩石损伤本构理论[J].岩土力学，1990，11（2）：67-71.
	Lu Yingfa，Ge Xiurun.Damage constitutive theory on rock[J].Rock and Soil Mechanics，1990，11（2）：67-71.
4	葛修润.岩石疲劳破坏的变形控制律、岩土力学试验的实时X射线CT扫描和边坡坝基抗滑稳定分析的新方法[J].岩土工程学报，2008，30（1）：1-20.
	Ge Xiurun.Deformation control law of rock fatigue failure，real-time X-ray CT scanning of geotechnical tests and new method for anti-sliding stability analysis of slope dam foundation[J].Chinese Journal of Geotechnical Engineering，2008，30（1）：1-20.
5	任建喜，蒋宇，葛修润.单轴压缩岩石疲劳寿命影响因素试验分析[J].岩土工程学报，2005，27（11）：47-50.
	Ren Jianxi，Jiang Yu，Ge Xiurun.Experimental analysis on influencing factors of fatigue life of uniaxial compression rock[J].Chinese Journal of Geotechnical Engineering，2005，27（11）：47-50.
6	肖建清.循环荷载作用下岩石疲劳特性的理论与实验研究[D].长沙：中南大学，2009.
	Xiao Jianqing.Theoretical and Experimental Study on Fatigue Properties of Rock Under Cyclic Loading[D].Changsha：Central South University，2009.
7	许江，鲜学福，王鸿，等.循环加、卸载条件下岩石类材料变形特性的实验研究[J].岩石力学与工程学报，2006，25（增1）：3040-3045.
	Xu Jiang，Xian Xuefu，Wang Hong，et al.Experimental study on deformation characteristics of rock materials under cyclic loading and unloading conditions[J].Journal of Rock Mechanics and Engineering，2006，25（Supp.1）：3040-3045.
8	Xiao J Q，Ding D X，Jiang F L，et al.Fatigue damage variable and evolution of rock subjected to cyclic loading[J].International Journal of Rock Mechanics and Mining Sciences，2010，47（3）：461-468.
9	Brooks A L.The impact of dose rate on the linear no threshold hypothesis[J].Chemico-Biological Interactions，2019， 301：68-80.
10	李树春，许江，陶云奇，等.岩石低周疲劳损伤模型与损伤变量表达方法[J].岩土力学，2009，30（6）：1611-1614.
	Li Shuchun，Xu Jiang，Tao Yunqi，et al.Rock low cycle fatigue damage model and damage variable expression method[J].Rock and Soil Mechanics，2009，30（6）：1611-1614.
11	尚德广.疲劳强度理论[M].北京：科学出版社，2017.
	Shang Deguang.Fatigue Strength Theory[M].Beijing：Science Press，2017.
12	许江，李树春，唐晓军，等.基于声发射的岩石疲劳损伤演化[J].北京科技大学学报，2009，31（1）：19-24.
	Xu Jiang，Li Shuchun，Tang Xiaojun，et al.Rock fatigue damage evolution based on acoustic emission[J].Journal of University of Science and Technology Beijing，2009，31（1）：19-24.
13	蒋宇，葛修润，任建喜.岩石疲劳破坏过程中的变形规律及声发射特性[J].岩石力学与工程学报，2004，23（11）：1810-1814.
	Jiang Yu，Ge Xiurun，Ren Jianxi.Deformation and acoustic emission characteristics of rock fatigue failure process[J].Chinese Journal of Rock Mechanics and Engineering，2004，23（11）：1810-1814.
14	郑孝军，胡志军，刘倡清，等.裂隙岩石疲劳损伤变形规律CT试验初探[J].西安科技大学学报，2005，25（4）：469-472.
	Zheng Xiaojun，Hu Zhijun，Liu Changqing，et al.Preliminary study on CT test of fatigue damage deformation law of fractured rock[J].Journal of Xi’an University of Science and Technology，2005，25（4）：469-472.
15	李树春，许江，杨春和，等.循环荷载下岩石损伤的CT细观试验研究[J].岩石力学与工程学报，2009，28（8）：1604-1609.
	Li Shuchun，Xu Jiang，Yang Chunhe，et al.CT meso-experimental study on rock damage under cyclic loading[J].Chinese Journal of Rock Mechanics and Engineering，2009，28（8）：1604-1609.
16	葛修润，任建喜，蒲毅彬，等.岩石疲劳损伤扩展规律CT细观分析初探[J].岩土工程学报，2001，23（2）：191-195.
	Ge Xiurun，Ren Jianxi，Pu Yibin，et al.Preliminary study on CT microscopic analysis of rock fatigue damage propagation law[J].Chinese Journal of Geotechnical Engineering，2001，23（2）：191-195.
17	Weng L，Wu Z J，Liu Q S.Evaluating damage and microcracking behavior of granite using NMR testing under different levels of unconfined compression[J].International Journal of Geomechanics，2019，19（1）：1-15.
18	李夕兵，翁磊，谢晓锋，等.动静载荷作用下含孔洞硬岩损伤演化的核磁共振特性试验研究[J].岩石力学与工程学报，2015，34（10）：1985-1993.
	Li Xibing，Weng Lei，Xie Xiaofeng，et al.Experimental study on NMR characteristics of hard rock damage evolution with pores under dynamic and static loads[J].Chinese Journal of Rock Mechanics and Engineering，2015，34（10）：1985-1993.
19	周科平，李杰林，许玉娟，等.冻融循环条件下岩石核磁共振特性的试验研究[J].岩石力学与工程学报，2012，31（4）：731-737.
	Zhou Keping，Li Jielin，Xu Yujuan，et al.Experimental study on nuclear magnetic resonance characteristics of rock under freeze-thaw cycles[J].Chinese Journal of Rock Mechanics and Engineering，2012，31（4）：731-737.
20	周科平，胡振襄，李杰林，等.基于核磁共振技术的大理岩卸荷损伤演化规律研究[J].岩石力学与工程学报，2014，33（增2）：3523-3530.
	Zhou Keping，Hu Zhenxiang，Li Jielin，et al.Research on evolution law of unloading damage of marble based on nuclear magnetic resonance technology[J].Chinese Journal of Rock Mechanics and Engineering，2014，33（Supp.2）：3523-3530.
21	王胜.用核磁共振分析岩石孔隙结构特征[J].新疆石油地质，2009，30（6）：768-770.
	Wang Sheng.Analysis of rock pore structure characteristics by nuclear magnetic resonance[J].Xinjiang Petroleum Geology，2009，30（6）：768-770.
22	Weng L，Wu Z J，Li X B.Mesodamage characteristics of rock with a pre-cut opening under combined static-dynamic loads：A nuclear magnetic resonance（NMR） investigation[J].Rock Mechanics and Rock Engineering，2018，51（8）：2339-2354.
23	蒋宇.周期荷载作用下岩石疲劳破坏及变形发展规律[D].上海：上海交通大学，2003.
	Jiang Yu.Fatigue Failure and Deformation Development of Rock Under Cyclic Loading [D].Shanghai：Shanghai Jiao Tong University，2003.
24	Liu Y，Dai F，Zhao T，et al.Numerical investigation of the dynamic properties of intermittent jointed rock models subjected to cyclic uniaxial compression[J].Rock Mechanics and Rock Engineering，2017，50（1）: 89-112.

Metrics

Viewed

Full text

Abstract

Cited

Shared

Discussed

岩样代号	编号	小孔谱面积		疲劳加载后增幅	大孔谱面积		疲劳加载后增幅
岩样代号	编号	疲劳前	疲劳后	疲劳加载后增幅	疲劳前	疲劳后	疲劳加载后增幅
0-19	1	7 765.15	7 865.13	+1.29%	6 088.45	6 530.75	+7.26%
	2	7 562.44	8 187.28	+8.26%	1 420.06	1 969.82	+38.71%
	3	7 209.69	7 990.78	+10.83%	5 592.66	6 159.69	+10.14%
0-26	1	8 025.26	6 854.49	-14.59%	2 408.64	3 473.45	+44.21%
	2	8 205.95	8 446.64	+2.93%	2 653.97	5 242.45	+97.53%
	3	6 612.31	8 041.24	+21.61%	2 721.09	6 020.57	+121.26%
0-31	1	8 019.32	7 611.89	-5.08%	2 626.23	5 901.92	+124.73%
	2	8 022.07	8 509.59	+6.08%	1 850.36	4 751.84	+156.81%
	3	7 888.17	7 936.17	+0.61%	2 687.42	5 587.12	+107.90%

裂隙倾角/（°）	拟合曲线方程	拟合系数R²	X=0.96的拟合数值
0	y=0.15421+0.58142*x^3.33836	0.97290	0.66156
15	y=0.14508+0.44167*x^10.39212	0.97241	0.43406
30	y=0.15864+0.50032*x^5.426	0.99970	0.55955
45	y=0.17174+0.34557*x^3.10133	0.93511	0.47622
60	y=0.13469+0.55907*x^6.46836	0.99831	0.56402

裂隙倾角/（°）	D与上限应力比的关系	D与上限应力（σ_max）的关系
0	D₀=1.14599*x^3.33836	D₀=1.14599*（σ_max/39.58）^3.33836
15	D₁₅=1.52838*x^10..39212	D₁₅=1.52838*（σ_max/33.66）^10..39212
30	D₃₀=1.24796*x^5.426	D₃₀=1.24796*（σ_max/35.75）^5.426
45	D₄₅=1.13495*x^3.10133	D₄₅=1.13495*（σ_max/37.72）^3.10133
60	D₆₀=1.30219*x^6.46836	D₆₀=1.30219*（σ_max/36.51）^6.46836

裂隙角度/（°）	D′与上限应力比的关系	D′与上限应力（σ_max）的关系
0	D₀′=0.2331+0.8789*x^3.33836	D₀′=0.2331+0.8789* （σ_max/39.58）^3.33836
15	D₁₅′=0.3342+1.0175*x^10.39212	D₁₅′=0.3342+1.0175* （σ_max/33.66）^10..39212
30	D₃₀′=0.2835+0.8941*x^5.426	D₃₀′=0.2835+0.8941* （σ_max/35.75）^5.426
45	D₄₅′=0.3606+0.7257*x^3.10133	D₄₅′=0.3606+0.7257* （σ_max/37.72）^3.10133
60	D₆₀′=0.2388+0.9912*x^6.46836	D₆₀′=0.2388+0.9912* （σ_max/36.51）^6.46836

[1]	李杰林, 李大千, 杨承业, 张童. 不同含水率下秦王川黄土抗剪强度与细观结构特征研究[J]. 黄金科学技术, 2024, 32(5): 860-870.
[2]	杜广盛,陈世江,武海龙. 温度影响下花岗岩宏、细观力学性质演化规律[J]. 黄金科学技术, 2022, 30(6): 935-947.
[3]	靳少博,刘科伟,黄进,靳绍虎. 单轴压缩下充填体损伤本构模型研究[J]. 黄金科学技术, 2021, 29(4): 555-563.
[4]	胡毕伟, 尹土兵, 李夕兵. 微波辐射辅助机械冲击破碎岩石动力学试验研究[J]. 黄金科学技术, 2020, 28(4): 521-530.
[5]	卓毓龙，王晓军，曹世荣,邓书强,李永欣，韩建文 . 渗流作用下稀土矿孔隙结构与强度弱化关系研究[J]. 黄金科学技术, 2017, 25(5): 101-106.

基于核磁共振T₂谱图的裂隙砂岩疲劳损伤分析

Fatigue Damage Analysis of Fractured Sandstone Based on Nuclear Magnetic Resonance T₂ Spectrum

RichHTML

PDF (PC)

摘要/Abstract

引用本文

使用本文

图/表 14

参考文献 24

相关文章 5

Metrics

本文评价

推荐阅读 0